Browsed byCategory: Raspberry Pi

The SDR hardware sold online usually includes an antenna. These antenna are not suitable to pickup radio transmissions that are low powered or distant. Here is an example of NOAA weather radio that is transmitted about 15 miles from my location. This first image is with the standard antenna shipped with the SDR adapter. The signal noise ratio is narrow, meaning the noise floor is high and the signal ceiling is low. The audio is noisy and hard to hear….

In this post I’ll be covering how to use SDR on Linux to capture data from wireless sensors using Benjamin Larrson’s RTL_433. I’ll start by covering the required install steps followed by some rudimentary examples. First you will need some kind of USB SDR hardware, this example we will be using the NooElec Nano. Here are the steps to install the RTL_433 software. Open a terminal window and enter in the following commands. sudo apt-get install libtool libusb-1.0.0-dev librtlsdr-dev rtl-sdr…

Working with thousands of image files captured from IP Cameras can be problematic. I’ve experienced issues with Caja hanging when simply browsing the folders that contain the captured images. To work around this, I compile video with FFMpeg from the image stock into a separate folder. First I’ll create a file list using this command ls /home/local/Videos/Security/IPCam3_20180726*.jpg > /home/local/Scripts/IPCam3_20180726.txt The results will then need to be processed so FFMpeg can use the file as a reference. Before – Not ready…

Security Monitoring with IP Cameras The market offers many choices when it comes to IP cameras. Most people who purchase these devices typically use the bundled software or hardware. This can be convenient but has it limitations. Many of the manufacturers do not support other brands of devices. In this post I’ll be covering how to gather imaging and video directly from IP cameras without the need for the vendors software or hardware solution. The camera I’ll be demonstrating in…

Many single board computers and mobile devices use microSD media as their primary data storage. However, microSD media is also used in cameras, security systems, and other small devices that handle large quantities of data. The security of this media format is often overlooked. In this post, we’ll look at some history around the topic of microSD security and its implications. I’ll also be covering some basic concepts of securing microSD media. MicroSD media is an extremely small form factor…

Peter Carcione made a youtube clip last year about Game Wizard’s adaptation of RetroPie, a game console emulator that plays video games from the early days of gaming. It runs on a Raspberry Pi and provides an all inclusive interface to run the various console platforms. He provides a step by step that still works as of this writing, you can find it here One of the things that I noticed was that the distro that RetroPie ran on was…

SoX offers quite a few ways to record audio. In this post, I’ll be covering how to record audio for the purposes of security. Home invasions are a sad fact of modern life for any number of reasons. I’ll show how to use SoX to capture audio so it can be added to the tools available to secure your personal belongings. One of the most simplest ways to get a recording from a microphone is to use the following commands….

Identifying RF Channels to monitor can be a time consuming effort. Using a standard non PC radio receiver can take a long time to identify a transmitting channel. Using RTL_Power and SDR FFT Spectrum Logging provided here (http://kmkeen.com/rtl-power/), makes the effort less challenging. RTL_Power will sweep through a range of radio frequencies at given steps and log the RF power levels detected by the USB SDR receiver. It does this over and over at set intervals to create a log…

In this post I’ll be giving some background and install steps on RTL-SDR. SDR stands for software defined radio and has been in use since the 1970s. Traditional radio processing is handled by hardware components like oscillators, regulators, and mixers. SDR replaces these functions with digital computer processing. RTL-SDR is a device that was originally designed to receive digital television transmissions, namely DVB-T TV using the RTL2832U chipset. The device is typically contained in a USB dongle. The RTL2832U chipset…

Dual Tone Multi Frequency signaling, commonly referred to as DTMF, is mainly used for phone dialing systems. But this isn’t the only use for DTMF signaling. Another common use is security access systems. In this post, I’ll be covering how to decode DTMF using MultiMon-NG. SoX will be used to record the DTMF signals generated on cell phones and keyless entry systems. I’ll be using a high gain directional microphone with a secondary microphone to cancel out background noise. SoX…